Full opinion text
II. Causation As their first issue, Dr. Gunn and OGA each argue that the evidence was legally insufficient to support the jury's finding that Dr. Gunn's alleged negligence caused Shannon's brain damage. In a legal sufficiency challenge, we consider whether the evidence at trial would enable a reasonable and fair-minded fact finder to reach the verdict under review. City of Keller v. Wilson , 168 S.W.3d 802, 827 (Tex. 2005). Evidence is legally insufficient to support a jury finding when (1) the record discloses a complete absence of evidence of a vital fact; (2) the court is barred by rules of law or of evidence from giving weight to the only evidence offered to prove a vital fact; (3) the evidence offered to prove a vital fact is no more than a mere scintilla; or (4) the evidence establishes conclusively the opposite of a vital fact. Bustamante v. Ponte , 529 S.W.3d 447, 455-56 (Tex. 2017) ; King Ranch, Inc. v. Chapman , 118 S.W.3d 742, 751 (Tex. 2003). The record contains more than a mere scintilla of evidence when the evidence rises to a level that would enable reasonable and fair-minded people to differ in their conclusions. King Ranch, Inc. , 118 S.W.3d at 751. Conversely, the record contains less than a scintilla when the evidence offered to prove a vital fact's existence is "so weak as to do no more than create a mere surmise or suspicion." Id. All the record evidence must be considered "in the light most favorable to the party in whose favor the verdict has been rendered," and "every reasonable inference deducible from the evidence is to be indulged in that party's favor." Bustamante , 529 S.W.3d at 456 (quoting Merrell Dow Pharmaceuticals, Inc. v. Havner , 953 S.W.2d 706, 711 (Tex. 1997) ). Recovery in a medical-malpractice case requires proof to a reasonable medical probability that the injuries complained of were proximately caused by the negligence of a defendant. Columbia Rio Grande Healthcare, L.P. v. Hawley , 284 S.W.3d 851, 860 (Tex. 2009). Proximate cause includes two components, cause-in-fact and foreseeability. Id. Proof that negligence was a cause-in-fact of the injury requires proof that (1) the negligence was a substantial factor in causing the injury, and (2) without the act or omission, the harm would not have occurred. Id. Thus, to satisfy a legal sufficiency review in such cases, plaintiffs must "adduce evidence of a 'reasonable medical probability' or 'reasonable probability' that their injuries were caused by the negligence of one or more defendants, meaning simply that it is 'more likely than not' that the ultimate harm or condition resulted from such negligence." Bustamante , 529 S.W.3d at 456 (quoting Jelinek v. Casas , 328 S.W.3d 526, 532-33 (Tex. 2010) ). In medical-malpractice cases, the general rule is that "expert testimony is necessary to establish causation as to medical conditions outside the common knowledge and experience of jurors." Jelinek , 328 S.W.3d at 533. The parties offer competing theories on causation. The court of appeals articulated McCoy's theory, which the jury apparently accepted: McCoy's causation theory is that Gunn failed to adequately treat Shannon's DIC by failing to order FFP to replace Shannon's clotting factors and slow her bleeding, and by failing to infuse enough units of blood. As Shannon continued to bleed, her body attempted various compensation mechanisms in an effort to maintain enough oxygen flow to avoid cardiovascular collapse and damage to her critical organs. However, Shannon continued to lose blood volume. As her blood volume loss approached the critical danger zone of approximately 40%, Shannon's body could no longer compensate, resulting in her cardiac arrest, lack of oxygen flow to her brain, and her permanent brain damage. 489 S.W.3d at 90. Dr. Gunn and OGA advanced a different theory-that Shannon's DIC caused small blood clots to form in Shannon's vascular system and some of those small clots lodged in blood vessels in Shannon's brain, resulting in her injuries. We summarize the evidence supporting the parties' arguments. A. McCoy's Theory For the standard of care and Dr. Gunn's alleged failure to meet it, McCoy relied upon the testimony of Dr. Molly Brewer, a medical doctor board certified in both obstetrics and gynecology and gynecological oncology. Dr. Brewer underwent specific training in handling DIC patients, and she taught "how to handle DIC from placental abruption and other causes" to other ob/gyns. Dr. Brewer testified that DIC impacts the body's ability to clot, which puts people at risk of bleeding because their clotting factors are no longer working properly. She stated that Shannon "absolutely" had DIC. Dr. Brewer estimated Shannon's blood volume based on her hemoglobin levels, explaining that "for every one point that the hemoglobin goes down, that's approximately equal to one unit of blood." She explained that doctors cannot always look at a patient and know if they are bleeding; therefore, doctors must rely on lab results, specifically hemoglobin levels, to approximate blood volume and blood loss. Based on this underlying assumption, Dr. Brewer testified that the decreased hemoglobin levels shown in Shannon's lab results indicated that she was losing blood. Specifically, the lab tests ordered at 7:20 a.m. indicated that Shannon's hemoglobin levels had dropped from 9.5 to 5.5, which "should have put [Dr. Gunn] into almost panic mode." Dr. Brewer testified that by 1:00 p.m., Shannon had lost about 33 to 44% of her blood volume. Lab results also indicated that Shannon's PT had increased, meaning that her blood was not clotting properly. Because DIC interfered with Shannon's body's clotting ability, Dr. Brewer stated that it was critical that she receive FFP and that Dr. Gunn breached the standard of care by failing to order or administer FFP in response to Shannon's lab results. [Y]ou can replace blood until the cows come home, but if you can't clot and you have an open wound like inside the uterus, they're going to continue to bleed. And so you basically put the blood in and the blood comes out, and without the clotting factors, you cannot control this coagulation disorder. According to Dr. Brewer, a reasonable and prudent physician managing DIC should be making calculations based on hemoglobin levels to justify blood transfusions (e.g., "her hemoglobin went from x to y and therefore, we assume that she's lost two units, three units, four units, and then it's appropriate to replace it"). She testified that Dr. Gunn breached the standard of care by failing to do these calculations and, on a broader level, by failing to create and document a cohesive plan to manage Shannon's DIC. Additionally, Dr. Brewer believed Shannon's lab results in the morning and the afternoon with respect to her other vital functions should have alerted Dr. Gunn that Shannon was losing blood due to her body's inability to clot. Dr. Brewer reported that Shannon's increased creatinine levels indicated that she had "acute renal failure," which, read in the context of DIC, tells us "[t]hat [she] probably doesn't have enough blood flow through [the] kidneys." She also pointed to Shannon's decreased oxygen saturation levels and her increased heart rate, describing these phenomena as compensation mechanisms to deal with low blood volume. "[I]f their blood is low, their heart rate goes up to get more blood.... If their oxygen is low, they breathe harder because it brings in more oxygen.... [T]hey actually shunt blood away from their kidneys because they want to spare the heart and ... the brain." Dr. Brewer stated that Shannon's low urine output was another sign of decreased blood flow to the kidneys, which should have been a warning sign. Instead of properly treating Shannon's low blood volume, Dr. Gunn administered Lasix, which is "for fluid overload" and probably made it worse for Shannon. She testified that a reasonable and prudent physician needs to stay equal with or ahead of blood loss in managing a patient like Shannon, and in this case, "Shannon was behind in her blood volume all the way along." According to Dr. Brewer, Dr. Gunn's failure to replace Shannon's clotting factors by administering FFP contributed to her developing uterine atony. In the afternoon, Shannon became agitated. Dr. Brewer described this as one of the cardinal signs "that she's going into cardiovascular collapse. I mean, something terrible has happened. Patients get agitated when they don't get enough oxygen." When asked about Shannon's oxygen saturation level of 72%, Dr. Brewer responded, "I think it's a crisis." Dr. Brewer testified that after about 1:00 p.m., "the d[i]e was cast with reasonable certainty. I mean, they were in serious trouble. This woman was dying in front of their eyes. I mean, she had blood pouring out." In looking at the whole picture and at the blood loss, Dr. Brewer said it was foreseeable that Shannon would go into ventricular fibrillation. "The problem was [ ] she had lost so much blood at that point that it was a disaster." Dr. Brewer stated that Shannon's lack of blood led to her ventricular fibrillation in the operating room. When a patient goes into ventricular fibrillation, her heart stops pumping blood and she is unable get oxygen to the brain. Shannon's EEG results indicated, "No focal or epileptic features are noted." Dr. Brewer testified that "the way that a reasonable person would interpret that is that something had happened to all of the brain.... A global injury." At St. Luke's there were seventeen neurologic consults, and each neurologist agreed that Shannon had anoxic encephalopathy, which is global damage to the brain caused by a lack of oxygen. Dr. Brewer offered the following conclusions: Dr. Gunn was negligent in failing to give more blood products from the beginning; Dr. Gunn was negligent in failing to order more frequent lab tests to determine whether the blood products needed to be adjusted; and Dr. Gunn was negligent in failing to include adjustments to the administration of blood products to deal with the hemoglobin, platelets, and lack of FFP. "You can [pour] the blood in, but the blood just keeps coming out if you can't clot it." B. Dr. Gunn and OGA's Theory Dr. Gunn and OGA produced three experts on the issue of liability: Dr. James Aubuchon, a medical doctor, board certified in anatomic and clinical pathology, blood banking, and transfusion medicine; Dr. James Alexander, a medical doctor, board certified in obstetrics and gynecology with a subspecialty of maternal/fetal medicine; and Dr. Martin Steiner, a neurologist. Contrary to Dr. Brewer's testimony, Dr. Aubuchon testified that with the blood products and fluids she had been given, Shannon had more than enough volume for her heart to function properly. He testified that her lab results (hemoglobin, creatinine, and PT), while outside of the normal ranges, were not "exceedingly high" or cause for panic. He also pointed to nurses' notes that recorded the presence of clots in the post-delivery vaginal bleeding, which "implies that the clotting system [was] able to work." The three experts collectively offered an alternative theory of liability. They testified that placental abruption is a result of a rupture of the mother's blood vessels in the uterus. This leads to the exposure of a substance known as thromboplastin. Thromboplastin is intended normally to start a clotting process in a small area, but in the case of placental abruption, it gets into the blood system and kicks off the clotting system inside the blood vessels themselves. This process is effectively DIC: an activation of the clotting system, such that small clots, or "thrombi," are being formed throughout the entire body. These small clots move through the vascular system, and if they move into even smaller vessels, they may block those vessels, which is called "microthrombus." Such blockage would prevent blood flow to surrounding tissues, causing those tissues to die from lack of oxygen. Dr. Steiner testified that Shannon's computerized axial tomography (CAT) scans after the injury were not consistent with a global hypoxic injury, but instead showed results focused in only a small area of the brain. Thus, he opined that "it's these microthrombi or these small little [clots] that we have been talking about" that cause the type of problems Shannon experienced. "It's not the type of thing that you see when there is a global hypoxia or a global lack of oxygen to the brain." He concluded that instead of a global or hypoxic event, Shannon suffered ischemia, or lack of blood flow to tissue, to small areas of her brain from these micro clots, and her neurological damage was "due to the small little microthrombi blocking off the blood vessels and causing teeny strokes." In support of this theory, he noted Shannon's initial improvement, which is typical in a patient who has mini strokes, but not in a patient who has suffered global problems of hypoxia to the brain. Thus, Dr. Steiner testified that Shannon's seizure in 2005, which he opined was unrelated to her initial brain injury, was significant because Shannon never regained the improved function she initially experienced. C. Competency of Evidence In analyzing whether there was legally sufficient evidence of causation, we start with the general proposition that "a determination of scientific reliability is appropriate in reviewing the legal sufficiency of evidence." Merck & Co. v. Garza , 347 S.W.3d 256, 262 (Tex. 2011). Justice Gonzalez, in writing for the Court, gave rather colorful examples of unreliable scientific evidence in E.I. du Pont de Nemours & Co. v. Robinson , 923 S.W.2d 549, 558 (Tex. 1995), when he said that even an expert with a degree should not be able to testify that the world is flat, that the moon is made of green cheese, or that the Earth is the center of the solar system. If for some reason such testimony were admitted in a trial without objection, would a reviewing court be obliged to accept it as some evidence? The answer is no. Havner , 953 S.W.2d at 712. Examination of an expert's underlying methodology is "a task for the trial court in its role as gatekeeper, and [is] not an analysis that should be undertaken for the first time on appeal." Coastal Transp. Co. v. Crown Cent. Petroleum Corp. , 136 S.W.3d 227, 233 (Tex. 2004). However, we have long held that incompetent evidence is legally insufficient to support a judgment, even if admitted without objection. City of Keller , 168 S.W.3d at 812 ; see also Coastal Transp. Co. , 136 S.W.3d at 233 (holding that a legal sufficiency challenge may be brought on appeal even when there was no admissibility objection to the reliability of the expert's opinion; in that case, the challenge is limited to the face of the record, "for example, when the expert testimony is speculative or conclusory on its face"); Hous. Unlimited, Inc. Metal Processing v. Mel Acres Ranch , 443 S.W.3d 820, 829 (Tex. 2014) (noting that an expert opinion admitted without objection may be probative evidence even if its basis is unreliable, but such opinion offered with no basis or with a basis that provides no support "is merely a conclusory statement and cannot be considered probative evidence, regardless of whether there is no objection"). Thus, evidence showing an expert's opinion to be incompetent cannot be disregarded, even if the result is contrary to the verdict. City of Keller , 168 S.W.3d at 812. And if an expert's opinion is based on certain assumptions about the facts, we must consider evidence showing those assumptions were unfounded. Id. at 813 ; see also Mel Acres Ranch , 443 S.W.3d at 829 (explaining that reliance on insufficient data and unsupported assumptions, as well as analytical gaps, can render an expert's opinion conclusory and without any evidentiary value). Thus, "if no basis for the opinion is offered, or the basis offered provides no support, the opinion is merely a conclusory statement and cannot be considered probative evidence, regardless of whether there is no objection." Mel Acres Ranch , 443 S.W.3d at 829. 1. The Hemoglobin Test Dr. Gunn challenges the underlying basis for Dr. Brewer's opinion-that one point on the hemoglobin test is equivalent to one unit of blood. At trial, Dr. Aubuchon testified that a hemoglobin test measures the concentration of hemoglobin in the blood, but "[i]t doesn't by itself say anything about how much blood the patient has." He testified that hemoglobin levels are impacted by a patient's hydration status: "If you were given a lot of IV fluids, that would cause your hemoglobin level, your concentration of hemoglobins, to go down." Thus, when Shannon's hemoglobin levels dropped to 5.5, he believed it was as a result of at least four liters of IV fluids she received prior to that. Moreover, Dr. Gunn argues that Dr. Brewer's testimony is contradictory because Shannon's lab results at 1:16 p.m. indicated that her hemoglobin levels had in fact increased from 5.5 to 7.5. An expert's opinion may be considered unreliable if it is based on assumed facts that vary materially from the actual facts, or if it is based on tests or data that do not support the conclusions reached. Whirlpool Corp. v. Camacho , 298 S.W.3d 631, 637 (Tex. 2009) ; see Mel Acres Ranch , 443 S.W.3d at 833. In either instance, the opinion is not probative evidence. Camacho , 298 S.W.3d at 637. However, this does not mean that an expert's factual assumptions must be uncontested or established as a matter of law-if the evidence conflicts, it is normally the province of the jury to determine which evidence to credit. Mel Acres Ranch , 443 S.W.3d at 833. But if the record contains no evidence supporting an expert's material factual assumptions, or if such assumptions are contrary to conclusively proven facts, opinion testimony founded on those assumptions is not competent evidence. Id. Expert testimony may also be unreliable if "there is simply too great an analytical gap between the data [relied upon] and the opinion proffered." Id. at 835 (quoting Gammill v. Jack Williams Chevrolet, Inc. , 972 S.W.2d 713, 726 (Tex. 1998) ). We are not required to ignore fatal gaps in an expert's analysis or assertions that are simply incorrect, and such a flaw in an expert's reasoning renders the scientific testimony "unreliable and, legally, no evidence." Id. (quoting Havner , 953 S.W.2d at 714 ). In her testimony, Dr. Brewer first offered a basis for using hemoglobin as an indicator of blood loss: Q: Now you hear about these blood tests like a CBC, a complete blood count. Is a hemoglobin included in the CBC? A: It is. Usually, a hemoglobin, hematocrits. It looks at white blood cells, it look[s] at red cells ... and it looks at platelet count. Q: If a physician wants to know if his or her patient is bleeding, can they order a CBC and look at hemoglobin ? A: They can. They can also just order a hemoglobin and a hematocrit. They can do either. She testified that using lab results, including hemoglobin, to measure blood loss is necessary because doctors "[a]bsolutely" cannot always look at a patient and know if she is bleeding. And Dr. Brewer explained the inconsistency in Shannon's increased hemoglobin level in the afternoon. Q: So what really was going on when the hemoglobin went from 5.5 at 7:27 in the morning to 7.5 at 1:16 in the afternoon, explain that to us please. A: That she was continuing to bleed. Q: And how do you know that? A: Because from the amount that was put in, that she was infused, it should have been higher than that. Finally, Dr. Brewer acknowledged that hemoglobin levels provide only an approximation of blood loss, repeatedly emphasizing on both direct and cross examinations that such levels must be viewed within the broader context of Shannon's condition. Q: ... But if [Shannon's hemoglobin ] was 5.5, that fact alone with no other evidence, you would agree one would not expect a patient to have a cardiac arrest just by having a 5.5 hemoglobin. Correct? A: I can't agree with what you're saying because you're taking things out of context. Q: Let's do this as-let's don't use Shannon McCoy. A: I don't think you can say it about any patient. It has to be in the context of what's happening medically. The court of appeals correctly noted that the jury was entitled to credit Dr. Brewer's testimony "that it is not 'appropriate' for someone managing a DIC case to consider just one lab result such as hemoglobin and ignore all the other markers, including the presence of quantifiable external bleeding." 489 S.W.3d at 93 (quoting Dr. Brewer's testimony). Thus, while the assumption underlying Dr. Brewer's opinion is not uncontested or established as a matter of law, it is also not unfounded or scientifically unreliable on the face of the record, and the jury was free to credit both the assumption and the opinion resting on it. City of Keller , 168 S.W.3d at 827 (holding that a reviewing court "must credit favorable evidence if reasonable jurors could and disregard contrary evidence unless reasonable jurors could not"). 2. The Quantity of Blood Products Transfused Applying Dr. Brewer's hemoglobin assumption, the court of appeals conducted detailed calculations of Shannon's blood loss based on the evidence in the record, reaching the following conclusions: Utilizing the initial blood volume figure of 20.1 units cited by Gunn and OGA, the jury reasonably could have concluded that Shannon's blood volume loss reached approximately 36% by 1:00 p.m. in reliance on these figures: • 20.1 units of blood present in Shannon's body at 11:00 a.m. on September 13 minus 13.2 units of blood lost plus 6 units of blood replaced equals 12.9 units of blood present at 1:00 p.m. on September 14. • 20.1 units of blood present in Shannon's body at 11:00 a.m. on September 13 minus 12.9 units of blood present at 1:00 p.m. on September 14 equals a net blood loss of 7.2 units during that interval. • A net blood loss of 7.2 units as of 1:00 p.m. on September 14 divided by 20.1 units of blood present at 11:00 a.m. on September 13 equals 36% of blood volume loss during that interval. This percentage falls squarely within Brewer's estimated blood volume loss range of 33% to 44%, and approaches the critical danger zone where it is undisputed on this record that cardiac arrest is a reasonable medical probability. 489 S.W.3d at 91-92. Dr. Gunn and OGA each argue that the court of appeals' assertion that Shannon received only "6 units of blood" is contrary to the record, and that prior to 1:00 p.m., she actually received at least 12 units of blood products. See id. at 92. This inconsistency reflects the confusion between "blood" and "blood products," implicating a quality-versus-quantity debate that persisted during oral argument before this Court. The court of appeals, relying on Dr. Brewer's hemoglobin assumption, included only the transfusions of packed red blood cells in its reference to "blood," see id. , while Dr. Gunn and OGA's calculation of "12 units of blood products" includes the two units of FFP and the four units of platelets that were administered in addition to the packed red blood cells. Dr. Brewer's theory operates under the apparent assumption that blood volume is primarily increased by transfusions of packed red blood cells, whereas transfusions of FFP and platelets have less effect on volume, but instead are administered to promote the clotting process. Again, here, it is the province of the jury to determine which evidence to credit, Mel Acres Ranch , 443 S.W.3d at 833, and we review evidence and inferences in the light most favorable to the jury's findings. Bustamante , 529 S.W.3d at 456. D. Superiority Requirement To avoid being conclusory, an expert must, to a reasonable degree of medical probability, explain how and why the negligence caused the injury. Jelinek , 328 S.W.3d at 536. Importantly, when the evidence demonstrates that "there are other plausible causes of the injury or condition that could be negated, the plaintiff must offer evidence excluding those causes with reasonable certainty." Bustamante , 529 S.W.3d at 456 (quoting Havner , 953 S.W.2d at 720 ) (no emphasis in original). Thus, when the facts support several possible conclusions, only some of which establish that the defendant's negligence caused the plaintiff's injury, the expert must explain to the fact finder why those conclusions are superior based on verifiable medical evidence, not simply the expert's opinion. Jelinek , 328 S.W.3d at 536. OGA asserts that the record contains no evidence that Dr. Brewer's blood-loss theory was superior to Dr. Aubuchon, Dr. Alexander, and Dr. Steiner's DIC/blood-clot theory. We disagree. McCoy's counsel addressed Jelinek 's superiority requirement head-on, asking Dr. Brewer directly to explain why her theory was medically superior to the theory advanced by the defense experts. In response, Dr. Brewer talked at length about what she perceived as gaps in Dr. Alexander's and Dr. Steiner's testimony. She also explained that Shannon's EEG was consistent with a global brain injury because it lacked the focal features that would be consistent with mini strokes to a specific area of the brain. This conclusion was consistent with the unanimous opinions of the seventeen neurologists who assessed and treated Shannon in the months following her injury. Dr. Brewer testified that the microthrombi study relied on by Dr. Steiner was invalid as applied to Shannon because it involved a patient population that already had brain damage, and thus was too dissimilar from Shannon to provide a useful comparison. And she testified that Shannon's lack of clotting based on her lab results rendered the defense's microthrombi theory "highly unlikely." Based on the record, Dr. Brewer's testimony more than satisfied Jelinek 's superiority requirement. See id. Like many medical-malpractice cases, this case involved a battle of the experts. See, e.g. , id. at 533. In such cases, jurors are the sole judges of the credibility of the witnesses and the weight to give their testimony. City of Keller , 168 S.W.3d at 819. It is the province of the jury to resolve conflicts in the evidence, and when reasonable jurors could resolve conflicting evidence either way, we presume they did so in accordance with the verdict. Id. at 820. The jury in this case heard conflicting expert opinions and it reasonably could have believed Dr. Brewer's testimony in light of the evidence. Id. ; see also Mel Acres Ranch , 443 S.W.3d at 833. We agree with the court of appeals that the evidence is legally sufficient to support a finding of proximate cause. III. Shannon's Future Medical Expenses Both Dr. Gunn and OGA assert that the trial court erred in refusing to admit video deposition testimony of Dr. Helen Schilling, which Dr. Gunn and OGA offered to controvert McCoy's evidence of the cost of future medical expenses. We review a trial court's exclusion of an expert witness's testimony for an abuse of discretion. Caffe Ribs, Inc. v. State , 487 S.W.3d 137, 142 (Tex. 2016). A trial court abuses its discretion by failing to follow guiding rules and principles. Hawley , 284 S.W.3d at 856. The court of appeals did not address the propriety of the decision to exclude Dr. Schilling's deposition testimony, concluding that even if its exclusion was in error, the error was harmless. 489 S.W.3d at 111. To reverse a trial court's judgment based on the exclusion of evidence, we must find that the trial court did in fact commit error, and that the error was harmful. Gee v. Liberty Mut. Fire Ins. Co. , 765 S.W.2d 394, 396 (Tex. 1989). We first assess whether Dr. Schilling's exclusion was in error and conclude that it was. At trial, McCoy presented evidence of future medical expenses through the testimony of Dr. Alex Willingham. When Dr. Gunn and OGA sought to present video deposition testimony from their own damages expert, Dr. Schilling, McCoy objected on the ground that the video cuts at issue did not contain the predicate to establish Dr. Schilling's qualifications as an expert witness. The trial court agreed and refused to allow the video deposition cuts on their own, but it acknowledged that Dr. Schilling could testify live at trial to establish the basis for her expertise. Dr. Gunn and OGA chose not to call Dr. Schilling as a live witness, but presented an offer of proof instead. To testify as an expert, a witness must be qualified, and the proposed testimony must be relevant to the issues in the case and based upon a reliable foundation. TEX. R. EVID. 702 ; Robinson , 923 S.W.2d at 556. Therefore, to be admissible, the specific video cuts at issue needed to contain Dr. Schilling's qualifications. If a court ruling excludes evidence, a party must preserve error by filing an offer of proof informing the court of the substance of the excluded evidence. TEX. R. EVID. 103. Dr. Gunn and OGA's offer of proof shows that Dr. Schilling's deposition provides adequate testimony as to her qualifications, including details about her background in physical medicine and rehabilitation, her experience teaching residents in that field, her experience as a director of rehabilitation at a hospital, her experience preparing life-care plans as part of her daily practice, and her own examination of Shannon. Based on the offer of proof, which references the transcript of the excluded testimony, Dr. Schilling's qualifications are not dissimilar from those of Dr. Willingham, whose testimony was admitted without objection. Both doctors completed a physical medicine and rehabilitation residency, served as medical directors at rehabilitation centers, are on a faculty teaching physical medicine and rehabilitation residents, and prepare life-care plans as part of their practices. Of course, without the specific video cuts in the record, we cannot determine with absolute certainty that the qualifications provided in the offer of proof (Dr. Schilling's deposition) were actually contained in the proffered testimony. To be clear, an offer of proof is not a work-around for the foundational requirement that an expert's qualifications be proven, and it is limited to the substance of the excluded evidence. See TEX. R. EVID. 103. However, based on the record before us, we are satisfied that the defense offered testimony of an expert witness whose qualifications were established. We have no reason to believe that the defense excluded its own expert witness's qualifications from the video cuts offered, nor can we conclude from the record before us that the qualifications discussed in the defense's offer of proof were in fact excluded from the video cuts that it intended to show the jury. Litigants in Texas are afforded a broad right to make strategic decisions when introducing evidence at trial, and they are entitled to present experts in a manner of their choosing, so long as it is consistent with the Texas Rules of Civil Procedure and the Texas Rules of Evidence. E.g. , Jones v. Colley , 820 S.W.2d 863, 866 (Tex. App.-Texarkana 1991, writ denied) ("A party, as a matter of trial strategy, is entitled to present his evidence in the order he believes constitutes the most effective presentation of his case, provided that it does not convey a distinctly false impression."). Our rules make deposition testimony admissible without regard to the party's availability to appear live. TEX. R. CIV. P. 203.6(b) ("All or part of a deposition may be used for any purpose in the same proceeding in which it was taken."); TEX. R. EVID. 801(e)(3) (indicating that a deponent's statement is not hearsay and "[t]he deponent's unavailability as a witness is not a requirement for admissibility"). Texas Rule of Civil Procedure 203.6 allows any part of a deposition to be presented in evidence, and no rule requires that the deposition be entered in its entirety. TEX. R. CIV. P. 203.6(b). On the contrary, the rule of optional completeness offers the adverse party a remedy if their sole objection to the deposition testimony is its completeness. TEX. R. EVID. 106 ("If a party introduces all or part of a writing or recorded statement, an adverse party may introduce, at that time, any other part ... that in fairness ought to be considered at the same time. 'Writing or recorded statement' includes depositions."); Jones , 820 S.W.2d at 866. OGA's attorney indicated at the time of the objection that Dr. Schilling's qualifications were contained in the proffered video cuts, and considering the deposition transcript, we see no reason to doubt that representation. Moreover, Dr. Schilling's qualifications were established in Dr. Gunn and OGA's offer of proof, referencing page and line numbers of the same deposition testimony they sought to present by video. Accordingly, we hold that the trial court abused its discretion in excluding Dr. Schilling's testimony. We next consider whether the exclusion of this evidence was harmful. Texas Rule of Appellate Procedure 61.1 recites our reversible error standard-under that standard, we may reverse the court of appeals' judgment only if the trial court's erroneous exclusion of evidence "probably caused the rendition of an improper judgment." TEX. R. APP. P. 61.1 ; see also Gee , 765 S.W.2d at 396. In application, a judgment may not be reversed unless the error "can be said to have contributed in a substantial way to bring about the adverse judgment." Lorusso v. Members Mut. Ins. Co. , 603 S.W.2d 818, 819-20 (Tex. 1980) (citing King v. Skelly , 452 S.W.2d 691, 696 (Tex. 1970) ). This rule is based on our understanding that "a litigant is not entitled to a perfect trial for, indeed, few trials are perfect." Id. at 819. The determination of whether the error probably caused the rendition of an improper judgment "necessarily is a judgment call entrusted to the sound discretion and good senses of the reviewing court," McCraw v. Maris , 828 S.W.2d 756, 759 (Tex. 1992), and we have recognized "the impossibility of establishing a specific test for determining harmful error." Caffe Ribs, Inc. , 487 S.W.3d at 145 (citing State v. Cent. Expressway Sign Assocs. , 302 S.W.3d 866, 870 (Tex. 2009) ); see also Lorusso , 603 S.W.2d at 821 (citing Standard Fire Ins. Co. v. Reese , 584 S.W.2d 835 (Tex. 1979) ). We have, however, noted that the role excluded evidence plays in the context of trial is important, and we have provided guidelines to assist trial courts in applying the reversible error standard. See Cent. Expressway Sign Assocs. , 302 S.W.3d at 870. Exclusion is likely harmless if the evidence was cumulative or if the rest of the evidence was so one-sided that the error likely made no difference in the judgment. Id. By contrast, exclusion of the evidence is likely harmful if it was "crucial to a key issue." Id. We do not dispute that future medical expenses, which made up almost 70% of the trial court's judgment, was indeed a "key issue." But that does not end the inquiry; our guidelines make clear that even if the exclusion of evidence is crucial to a key issue, it is "likely harmful," not conclusively or per se harmful. See id. (emphasis added). And our guidelines do not displace the standard-otherwise the standard would become meaningless for entire categories of error. See In re D.I.B. , 988 S.W.2d 753, 759 (Tex. 1999) ("[A]ppellate courts should not automatically foreclose the application of the harmless error test to certain categories of error." (quoting Cain v. State , 947 S.W.2d 262, 264 (Tex. Crim. App. 1997) ) ); Walker v. Tex. Emp'rs' Ins. Ass'n , 155 Tex. 617, 291 S.W.2d 298, 301 (1956) ("Reversal may not be predicated upon a simple showing that error occurred and that the jury returned a verdict in some respects favorable to the party the error was reasonably calculated to help. If it could, the further provision of [the predecessor to Rule 61.1 ] that it must also appear that the error 'probably did cause the rendition of an improper judgment' would be meaningless and pointless."). Thus, in determining whether the exclusion of evidence was harmful, we must review the entire record, Tex. Dept. of Transp. v. Able , 35 S.W.3d 608, 617 (Tex. 2000), and we apply the same standard-whether the erroneous exclusion of evidence probably caused the rendition of an improper judgment-even when the excluded evidence related to a key issue. Caffe Ribs, Inc. , 487 S.W.3d at 144-45 ; Gee , 765 S.W.2d at 396. The dissent manipulates the language we have used in analyzing whether error is harmful by omitting the word "likely" from our guidelines and introducing a two-part "framework" under which an error "is considered to have caused rendition of an improper judgment ... if the excluded testimony was crucial to a key issue, provided that the excluded evidence was not merely cumulative and that the other evidence was not so one-sided that the excluded evidence likely would have made no difference." 554 S.W.3d at 681. However, we have never endorsed this standard and have in fact noted that establishing a bright-line rule-as the dissent proposes to do-is impossible. Caffe Ribs, Inc. , 487 S.W.3d at 145 ; see also Lorusso , 603 S.W.2d at 821 ("We recognize the impossibility of prescribing a specific test for determining whether any error ... did cause the rendition of an improper judgment. Such a determination necessarily is a judgment call entrusted to the sound discretion and good senses of the reviewing court.") (internal quotations omitted). Our standard does not require that a complaining party show that evidence was not cumulative, not so one-sided, or even crucial to a key issue. "The complaining party must only show that the exclusion of evidence probably resulted in rendition of an improper judgment." Cent. Expressway Sign Assocs. , 302 S.W.3d at 869 (internal quotations omitted). Dr. Gunn and OGA explained to the trial court that Dr. Schilling's video deposition testimony revolved around her line-item annotations to the life-care plan that Dr. Willingham had prepared, and in their offer of proof, they tendered Dr. Schilling's marked-up copy of Dr. Willingham's life-care plan for Shannon to be admitted into the record. Dr. Gunn and OGA argued that the excluded video testimony indicated that Dr. Schilling believed some items in Dr. Willingham's life-care plan were not reasonably necessary, and that Dr. Schilling believed some items in that life-care plan related to Shannon's subsequent conditions (her seizure and hypoxia in 2005) and thus were unrelated to Dr. Gunn's alleged negligence. Dr. Willingham's life-care plan projected future medical expenses for two care options, one for home care (Option 1) and one for facility-based care (Option 2). The two options were clearly presented to the jury. Both plans accounted for a twenty-year life expectancy. Dr. Willingham's testimony enumerated a number of categories of expenses-physician services, therapeutic services, medication, diagnostics, and supported life care, among others. He explained in detail what each category entailed, and he discussed why the projected expenses for some categories were the same for Option 1 and Option 2 while others were different for the two options. He testified that, in total, the projected future medical expenses were "just over $6.9 million" for Option 1 and "just over $7.3 million" for Option 2. He then explained that Dr. Schilling had made annotations to his life-care plan, "getting rid of some items and reducing the frequency of some items and lowering the cost of some items." He testified that implementing Dr. Schilling's changes and criticisms reduced the projected costs to $3.3 million for Option 1 and $6.7 million for Option 2. Neither of the two witnesses' testimony purported to speak to liability, which the jury ultimately decided in favor of McCoy. Therefore, although the exclusion of Dr. Schilling's video testimony was error, we are satisfied that the exclusion did not affect the jury's determination of liability. Nor did it cause the rendition of an improper judgment with regard to awarding future medical expenses, since both experts conceded that Shannon would require several millions of dollars in future medical expenses. And the parties do not dispute that the amount of Shannon's future medical expenses would be at least equal to Dr. Schilling's reduced projections for Option 1 and Option 2-a minimum of $3.3 million. Thus, the only harm that could have resulted from the exclusion of Dr. Schilling's testimony was with respect to the amount of the award for future medical expenses that exceeded Dr. Schilling's minimum projection of $3.3 million. Furthermore, neither Dr. Willingham's testimony nor Dr. Schilling's proffered video testimony attempted to persuade the jury that one option was preferable to the other. On the contrary, Dr. Willingham specifically stated on cross examination that he was not making a judgment call as to which option was preferable: "Either venue is appropriate, either care remaining within the home with caregivers brought in or moving to a life care residential. Either venue is appropriate." Likewise, Dr. Schilling's excluded deposition testimony contains nothing that might have suggested to the jury that home care would have been preferable. The jury was presented with ample testimony to understand the nature of the two options and chose Option 2, facility-based care. Thus, the question is what effect, if any, the erroneous exclusion of Dr. Schilling's video testimony had on the amount of damages awarded under the Option 2 plan, and whether the exclusion probably caused the jury to improperly award future medical expenses in excess of her projection for that option, $6.7 million. Dr. Gunn and OGA do not challenge the legal sufficiency of the evidence supporting the jury's award of future medical expenses; therefore, that issue is not before us. We note that there is evidence to support Dr. Willingham's projected expenses, and the jury was presented with some evidence of Dr. Schilling's projections and criticisms. An award of future medical expenses is, by its very nature, not a matter of certainty. See, e.g. , Gulf, C. & S.F. Ry. Co. v. Harriett , 80 Tex. 73, 15 S.W. 556, 559 (1891) ("[T]he evidence should show that there is a reasonable probability of the occurrence of future ill effects of the injury, and [ ] it need show no more in order to justify the jury in considering future consequences in estimating the damages."); see also Rosenboom Mach. & Tool, Inc. v. Machala , 995 S.W.2d 817, 828 (Tex. App.-Houston [1st Dist.] 1999, pet. denied) (explaining that, to recover future medical expenses, "the plaintiff must present evidence to establish that in all reasonable probability, future medical care will be required and the reasonable cost of that care"). The fact that additional evidence might have led the jury to award a different amount of future medical expenses does not mean that the jury's award without that evidence was unsupportable or improper. See Aultman v. Dallas Ry. & Terminal Co. , 152 Tex. 509, 260 S.W.2d 596, 600 (1953) (discussing the meaning of "probably" and recognizing that error can be harmless when it has no bearing on the issue of liability and could have influenced only the amount of damages, and the record contains ample support for the damages award). At the end of the day, we afford the jury discretion in awarding damages within the range of evidence presented at trial. Sw. Energy Prod. Co. v. Berry-Helfand , 491 S.W.3d 699, 713 (Tex. 2016) (explaining that when determining whether the jury had a sufficient evidentiary foundation on which to base its damages award, we limit our review to only the evidence tending to support the jury's damages award, unless contrary evidence is conclusive). An error in excluding evidence is harmful when it "probably" caused the rendition of an improper judgment, and "probably" is a higher standard than "might" or "could have." See Caffe Ribs, Inc. , 487 S.W.3d at 144-45 (stating that a trial court's exclusion of evidence "is reversible only if it probably caused the rendition of an improper judgment"); Aultman , 260 S.W.2d at 600 (defining "probably" as "having more evidence for than against; supported by evidence which inclines the mind to believe, but leaves some room for doubt; likely"). Of course, this standard does not require the complaining party to prove that " 'but for' the exclusion of evidence, a different judgment would necessarily have resulted." Cent. Expressway Sign Assocs. , 302 S.W.3d at 870. But "likely" does not mean "definitively"-we must review the record to determine whether, in this particular case, the exclusion of Dr. Schilling's video deposition testimony "probably," as opposed to "might have" or "could have," caused the rendition of an improper judgment. Having reviewed the entire record, we cannot say that the erroneous exclusion of Dr. Schilling's video deposition testimony probably caused the rendition of an improper judgment. Dr. Gunn and OGA have not shown the trial court's error to be harmful, and we therefore may not reverse on this basis. TEX. R. APP. P. 61.1. This is, of course, not to say that a plaintiff can effectively preempt a defense expert's presentation of evidence or a witness by having one of the plaintiff's expert witnesses discuss the substance of the defense witness's testimony. That cannot be the case. We hold only that in this case, on the record before us, the exclusion of Dr. Schilling's testimony did not "probably cause the rendition of an improper judgment." Id. ; see Caffe Ribs, Inc. , 487 S.W.3d at 144-45 ; Gee , 765 S.W.2d at 396. IV. Medical Billing Affidavits As their second and third issues respectively, Dr. Gunn and OGA argue that McCoy failed to present legally sufficient evidence of Shannon's past medical expenses, for which the jury awarded $703,985.98. Specifically, they argue that the affidavits McCoy served did not comply with Texas Civil Practice and Remedies Code section 18.001 and therefore constituted no evidence, and in the absence of proper affidavits, McCoy failed to provide expert testimony regarding the reasonableness and necessity of the fees. Section 18.001 governs proving expenses by affidavit. TEX. CIV. PRAC. & REM. CODE § 18.001. It is common to use section 18.001 affidavits as evidence of the reasonableness and necessity of past medical expenses. See, e.g. , Haygood v. De Escabedo , 356 S.W.3d 390, 397-99 (Tex. 2011). The statute provides: Unless a controverting affidavit is served as provided by this section, an affidavit that the amount a person charged for a service was reasonable at the time and place that the service was provided and that the service was necessary is sufficient evidence to support a finding of fact by judge or jury that the amount charged was reasonable or that the service was necessary. TEX. CIV. PRAC. & REM. CODE § 18.001(b). To comply with this section, an affidavit must be made by "(A) the person who provided the service; or (B) the person in charge of records showing the service provided and the charge made." Id. § 18.001(c)(2). Consistent with other parts of the Code, the amount listed on the affidavit is limited to the amount actually paid or incurred, not the amount billed. Haygood , 356 S.W.3d at 390, 398 (citing TEX. CIV. PRAC. & REM. CODE § 41.0105 ). Generally speaking, section 18.001 is "purely procedural, providing for the use of affidavits to streamline proof of the reasonableness and necessity of medical expenses." Id. at 397. Thus, the affidavits are not conclusive; the statute expressly provides that they can be controverted by competing affidavit. TEX. CIV. PRAC. & REM. CODE § 18.001(b) ; Haygood , 356 S.W.3d at 397-98. McCoy initially served fourteen section 18.001 affidavits from Shannon's medical providers or those providers' record custodians, containing the billed amounts. After this Court issued its opinion in Haygood , McCoy withdrew the provider affidavits and filed affidavits from subrogation agents for health insurance carriers that had paid Shannon's medical expenses, reflecting instead the amounts actually paid. Dr. Gunn and OGA objected, arguing that section 18.001 limits the proper affiants to providers or record custodians for those providers. We disagree. Our primary goal in statutory construction is to give effect to the Legislature's intent. Tex. Lottery Comm'n v. First State Bank of DeQueen , 325 S.W.3d 628, 635 (Tex. 2010). We rely on the plain meaning of the text as expressing legislative intent unless a different meaning is supplied by legislative definition or is apparent from the context, or the plain meaning leads to absurd results. Id. We have already acknowledged that the Legislature's intent in enacting section 18.001 was "to streamline proof of the reasonableness and necessity of medical expenses." Haygood , 356 S.W.3d at 397. We further note that the plain language of section 18.001(c)(2)(B) does not require that affidavits be made by a records custodian for a medical provider . TEX. CIV. PRAC. & REM. CODE § 18.001(c)(2)(B) ; see also Tex. Mut. Ins. Co. v. Ruttiger , 381 S.W.3d 430, 452 (Tex. 2012) ("[T]his Court presumes the Legislature deliberately and purposefully selects words and phrases it enacts, as well as deliberately and purposefully omits words and phrases it does not enact."). Still, we recognize that an effort to "streamline" proof of the reasonableness and necessity of medical expenses cannot negate the requirement that reasonableness and necessity be in fact proven by legally sufficient evidence. See Haygood , 356 S.W.3d at 397-98. We therefore assess whether subrogation agents are in a position to testify to the reasonableness and necessity of medical expenses. Health care costs today are complex, and the price of a particular provider's services may depend on many factors, including geography, experience, location, government payment methods, and the desire to make a profit. Keith T. Peters, What Have We Here? The Need for Transparent Pricing and Quality Information in Health Care: Creation of an SEC for Health Care , 10 J. HEALTH CARE L. & POL'Y 363, 366 (2007). Hospitals have developed a two-tier pricing system: (1) the "list price," which serves as a starting point for negotiations, similar to the sticker price one might find when purchasing a vehicle; and (2) the "actual price," which is what private insurers, Medicaid and Medicare, and other groups actually pay after negotiations. Id. ; Haygood , 356 S.W.3d at 393. While hospital prices ideally should be determined by the cost of providing care, in reality list prices are driven in large part by the reimbursement rates for federal programs such as Medicare and Medicaid, and by negotiations with private insurers. Haygood , 356 S.W.3d at 393 (citing Peters, supra at 366 ). Although the list price of health care varies widely across different regions of the country, the actual price paid is relatively static. Peters, supra at 366. Thus, it is not uncommon or surprising that a given medical provider may have no basis for knowing what is a "reasonable" fee for a specific service. See id. at 364 (discussing the lack of transparency in health care pricing and detailing a personal account in which the business office of a hospital "did not know and had no list of typical charges" for the cost of delivering a child, a routine procedure). While hospitals may devote significant time and effort to establishing and updating their list prices, they generally establish those prices with the clear expectation that they will be paid only a portion of them. George A. Nation III, Obscene Contracts: The Doctrine of Unconscionability and Hospital Billing of the Uninsured , 94 KY. L.J. 101, 118 (2005). Thus, for most consumers today, the most important function of a health insurance company in a given year is not paying a portion of health care expenses, but negotiating the prices for those services with providers. Jackson Williams, The Persistence of Opportunistic Business Models in Health Care and a Stronger Role for Insurance Regulators in Containing Health Care Costs , 41 NOVA L. REV. 313, 315 (2017). We have previously noted that agreements between willing providers and willing insurers can yield reasonable rates. See Haygood , 356 S.W.3d at 393-94. Insurance companies, which insure consumers across the nation, regularly negotiate with providers to agree upon the actual prices. See id. at 393 ; Williams, supra at 315. Moreover, insurance companies keep records and databases of both the list prices and the actual prices of specific treatments and procedures, though they may not pass this information to consumers. See Peters, supra at 375 (noting as examples that Blue Cross and Blue Shield of North Carolina provides the low, high, and average retail prices of specific procedures on its website, and that Aetna initiated a controversial pilot program in 2005 making information on the actual price for common procedures available to its insureds). Thus, with national and regional bases on which to compare prices actually paid, insurance agents are generally well-suited to determine the reasonableness of medical expenses. In determining the necessity of medical expenses, it is beyond argument that medical providers-doctors-are in the best position to determine what treatments or procedures and resulting expenses are "necessary." So of course, ideally, medical providers themselves would testify to the necessity of medical expenses. However, by drafting section 18.001 to allow either "the person who provided the service" or the "person in charge of records" to testify to reasonableness and necessity, the Legislature has acknowledged and made allowance for the reality that the ideal paradigm does not reflect today's complex health care system. And, for better or for worse, in the context of our health care system, what is "necessary" is often heavily influenced by insurance companies and by what treatments and procedures they are willing to cover. Janet L. Dolgin, Unhealthy Determinations: Controlling "Medical Necessity," 22 VA. J. SOC. POL'Y & L. 435, 442-43 (2015) (explaining that the insurance industry sits at the center of the delivery and coverage of health care in the United States and occupies "a privileged position in rendering medical necessity determinations-the rationale in terms of which health care is apportioned"). Thus, the plain language of section 18.001 does not limit the proper affiants to medical providers and medical providers' record custodians, and the reality of our health care system does not mandate such a limitation in order to establish the reasonableness and necessity of expenses. By contrast, the dissent's argument would read into the statute that an affidavit must be made by a records custodian "sufficiently trained or experienced in medicine to give competent testimony as to the necessity of treatment and sufficiently familiar with reasonableness of charges in the region or locale in which services were rendered to give competent testimony as to the reasonableness of amounts paid by insurance companies," as well requiring that an affiant be "reasonably connected to the patient" or have "first-hand knowledge of the services rendered." But see TGS-NOPEC Geophysical Co. v. Combs , 340 S.W.3d 432, 439 (Tex. 2011) ("We presume that the Legislature chooses a statute's language with care, including each word chosen for a purpose, while purposefully omitting words not chosen."). These heightened requirements do not appear in the language of the statute, nor do they comport with the Legislature's intent to streamline proof of the reasonableness and necessity of medical expenses. See Haygood , 356 S.W.3d at 397. We note that in this case, McCoy did produce affidavits from the medical providers or the providers' records custodians, which were later rendered insufficient by our decision in Haygood because they reflected only the amount billed. See 356 S.W.3d at 398-99. If we were to hold that the subrogation agents' affidavits were also insufficient, as the dissent advocates and Dr. Gunn and OGA would have us do, we would in effect render the Legislature's streamlined proof procedure a complicated trap requiring plaintiffs to provide two sets of affidavits: (1) affidavits as to necessity of treatment from medical providers with actual knowledge of the patient's treatment, or their record custodians; and (2) separate affidavits as to reasonableness of paid charges from local or regional insurance agents or someone else with knowledge of customary amounts paid for particular treatments in that particular region. Such an approach would frustrate the Legislature's intent. We reiterate that an affidavit served under section 18.001 is "purely procedural" and does not amount to conclusive evidence of the expenses. See TEX. CIV. PRAC. & REM. CODE § 18.001 ; Haygood , 356 S.W.3d at 397-98. The statute "expressly contemplates that the issue can be controverted by affidavit." Haygood , 356 S.W.3d at 397 ; accord. TEX. CIV. PRAC. & REM. CODE § 18.001. We hold that the affidavits served by McCoy were proper and constituted legally sufficient evidence of the reasonableness and necessity of Shannon's past medical fees. V. Jury Instruction At trial, Dr. Gunn and OGA requested the following instruction, which the trial court refused: "An occurrence may be an 'unavoidable accident,' that is, an event not proximately caused by the negligence of any party to the occurrence." They now argue that the trial court committed harmful error by refusing to include their requested instruction in the jury charge. A trial court has considerable discretion to determine proper jury instructions, and we review a trial court's decision to submit or refuse a particular instruction for an abuse of discretion. Thota v. Young , 366 S.W.3d 678, 687 (Tex. 2012). One way in which a trial court may abuse its discretion is by failing to follow guiding rules and principles. Hawley , 284 S.W.3d at 856. An instruction is proper if it assists the jury, accurately states the law, and finds support in the pleadings and evidence. Id. at 855. Still, we do not reverse a judgment based on charge error unless the error probably caused the rendition of an improper judgment or prevented the petitioner from properly presenting the case to the appellate courts. TEX. R. APP. P. 61.1. Thus, when a trial court refuses to submit a requested instruction that is otherwise proper, the question on appeal is whether the request was reasonably necessary to enable the jury to render a proper verdict. Shupe v. Lingafelter , 192 S.W.3d 577, 579 (Tex. 2006) (per curiam) (citing Tex. Workers' Comp. Ins. Fund v. Mandlbauer , 34 S.W.3d 909, 912 (Tex. 2000) ). An unavoidable accident is "an event not proximately caused by the negligence of any party to it." Reinhart v. Young , 906 S.W.2d 471, 472 (Tex. 1995). The purpose of the unavoidable-accident instruction is to advise the jurors that "they do not have to place blame on a party to the suit if the evidence shows that conditions beyond the party's control caused the accident." Dillard v. Tex. Elec. Coop. , 157 S.W.3d 429, 432 (Tex. 2005) (citing Reinhart , 906 S.W.2d at 472 ). An instruction on unavoidable accident is "most often used to inquire about the causal effect of some physical condition or circumstance such as fog, snow, sleet, wet or slick pavement, or obstruction of view, or to resolve a case involving a very young child who is legally incapable of negligence." Reinhart , 906 S.W.2d at 472. But the instruction is not limited to only those circumstances-it merely informs the jury that it may consider causes of the occurrence other than the negligence of the parties. Dillard, 157 S.W.3d at 433. In any case, such an instruction is proper only when there is evidence that the e